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Decision Making in Ultrasonic Instrumentation

EDWARD OLIVE/ ISTOCK/THINKSTOCK

Sufficient power, proper adaptation, and appropriate stroke activation are integral to successful use of this modality.

By Stacy A. Matsuda, RDH, BS, MS

Dental hygiene practitioners face a daunting task in the provision of
nonsurgical periodontal therapy. Countless choices must be made in a short
timeframe regarding procedure, delivery method, and armamentarium. When coupled
with clinical protocol and technique, all facets of care can impact the success
of therapy.

For all of the painstaking efforts made to eradicate periodontal
breakdown in patients, dental hygienists sometimes get in the way of their own
success. The unintentional misuse of ultrasonic instrumentation is often one of
these roadblocks. Because ultrasonic instrumentation may appear easier than
hand instrumentation, clinicians may implement a less vigilant, casual
approach. The three keys to successful ultrasonic therapy are sufficient power,
proper adaptation, and appropriate stroke activation.

Power Level

Power level
is a critical consideration in ultrasonic instrumentation.1 The
prevailing thought in the 1980s was to use low power for all debridement. This
line of thinking suggested that calculus didn't matter—it was more important to
preserve root structure. Thin ultrasonic inserts/tips (UITs) were used at low
power settings, which rapidly burnished the outer surface of the calculus
without removing it. Partially scaled burnished calculus left on root surfaces
becomes a reservoir for periodontal pathogens, as evidenced by endoscopic
studies.2 An ulcerated lesion mimicking the shape of the retained
calculus persists, as the chronic inflammatory process continues. These areas
of burnished deposit are impervious to detection and also removal, jeopardizing
periodontal health.3

FIGURE 1. A Hirschfeld 3/7 is inserted in the area of bleeding on probing.

FIGURE 2. The coronal pull
stroke moves straight in the
direction of the terminal shank, no
matter how it is positioned on the
tooth (lingual approach shown).

FIGURE 3. Horizontal, vertical, and oblique strokes should be used with
Hirschfeld files.

FIGURE 4. File use should be followed by mini-bladed Gracey curets in multidirectional,
overlapping strokes. A mini-bladed Gracey 5/6 curet is shown.

FIGURE 5. Overlapping strokes confined to vertical channels that traverse the
tooth ensure thorough coverage. Begin at the gingival margin and overlap strokes,
moving apically until the attachment is reached. Visualize each vertical channel
and cover comprehensively before moving forward.

FIGURE 6. Ultrasonic
inserts/tips may appear to
cover a broad surface
(yellow bar) when adapted
to roots, but each stroke
forms a track of only 1 mm
to 2 mm at the terminal
end (green bar),
necessitating careful
overlap for full coverage.

FIGURE 7. The
lateral surface of
the piezoelectric
tip is adapted to
the buccal
surface.

FIGURE 8. To maintain lateral tip adaptation to the mesial surface, the handle
must pivot at the line angle.

When results
fall short of intended goals at reevaluation, patients may be given local
delivery antibiotics as an adjunct to mechanical therapy, which can temporarily
reduce inflammation and forestall periodontal destruction. Adjuncts to
mechanical therapy, however, cannot eliminate the source of inflammation. The
mineralized scaffold of burnished calculus keeping the pathogens in contact
with the overlying soft tissue must be removed in order for the tissue to
properly heal.4

Technique

The nonsurgical
solution to removing burnished calculus is a definitive treatment protocol,
based on thorough assessment. Burnished calculus typically cannot be felt
tactilely, making it difficult to detect. The one reliable clue that burnished
calculus is present is bleeding on probing,1,5 which is often seen
as a faint hairline of blood, sometimes evident after probing is complete.
Clinicians should document any areas that exhibit this clinical sign of minor
bleeding on probing and treat as follows:

Begin with
a sharp Hirschfeld file (3/7 and/or 5/11) and insert subgingivally in the
vicinity of bleeding (Figure 1). As with any periodontal therapy, use local
anesthesia to facilitate thorough and comfortable treatment.

Confirm
contact with the soft tissue attachment with the head of the instrument. Using
light to moderate lateral pressure, activate a series of coronal pull strokes
in line with the terminal shank and the root surface (Figure 2). The Hirschfeld
file will fracture the residual burnished calculus. Use vertical, oblique,
and—if possible—horizontal strokes to cross-hatch the root surface with
overlapping strokes (Figure 3). Keep the vector of movement parallel to the
root surface.

Switch to
sharp, mini-bladed Gracey curets (5/6, 11/12, 13/14) to root plane surfaces
that have been treated with the file. This is a necessary step after the use of
Hirschfeld files. Use multidirectional overlapping strokes to ensure
comprehensive coverage (Figure 4).

Follow
manual root planing with ultrasonic instrumentation—preferably a slender
beveled tip on medium-high or high power. Activate the tip with confined,
overlapping strokes in slow, methodical channeling (Figure 5). Worn
out UITs deliver insufficient power for deposit removal, resulting in burnished
calculus.6 Monitor tip wear using a template to ensure adequate
power transfer for calculus removal.

Evaluate
the treated area(s) in 6 weeks and compare to previous data. Observe closely
for slight bleeding on probing, which should be absent if burnished calculus
has been eliminated.

Adaptation

Proper
adaptation is key to the success of ultrasonic therapy.7 The
terminal 2 mm of the UIT must be held in contact with the root surface as it
progresses around the dentition (Figure 6). Energy transfer is at its
maximum at the terminal 1 mm to 3 mm of the tip. Positioning the UIT so that
any part of the shank above 3 mm is in contact with the tooth will not provide
adequate energy capable of disrupting mineralized deposits. Clinicians need to
visualize root morphology and refer to the radiographs when activating UITs
subgingivally. In this way, the terminal 2 mm can be kept adapted with greater
confidence.

Piezoelectric
technology is most successful when the sides of the tip are used.1
The handpiece should pivot at all line angles (Figure 7 and Figure 8)
to keep the lateral edge of the tip adapted to the tooth as the clinician
progresses from surface to surface.8

Activation

Activation—the
manner in which the UIT is moved across the root surface—is also important to
the success of ultrasonic instrumentation.9 When first introduced to
ultrasonic therapy, students are taught the principle of keeping the UIT in
constant motion to prevent damage to the tooth—a critical notion for the novice
clinician. The emphasis on avoiding thermal and structural damage to the tooth
is appropriate. In an introductory laboratory setting, this generally results
in fast and furious strokes performed in random scribble patterns, a habit that
becomes ingrained in muscle memory. To break this habit, clinicians need to
make a conscious effort to form new neural pathways of muscle memory that
support the preferred technique.

Several
elements are key to performing ultrasonic stroke activation. The first is
visualization of the root surface to create small segments of coverage (Figure
5).9 Rather than attempt to cover an entire buccal surface of a
molar, the surface should be broken up into vertical channels so that comprehensive
coverage can be achieved.10,11

The second
element is the speed of movement across the root surface. Mineralized deposits
cannot be raced across because the energy transfer must be powerful enough to
shatter the calculus and cleave it cleanly away from the surface. Brisk,
feathery strokes across the span of deposit, while suitable for biofilm
removal, tend to burnish calculus. Use slow, methodical overlapping strokes
moving from the coronal-most border of the deposit toward the soft tissue
attachment to achieve clean calculus removal millimeter by millimeter.10

Once
ultrasonic therapy is complete, follow with mini-bladed and regular Gracey
curets to access concavities and deep contours of root surfaces, such as
furcations and proximal surfaces. The rationale for this is simple geometry:
blade curvatures conform intimately to the curved contours of root structure
where the straight surface profiles of UITs have not fully accessed. The last
element in stroke activation is performing a final flush with precision thin
UITs wherever hand instrumentation occurred.

Conclusion

Ultrasonic
therapy provides major ergonomic and therapeutic advantages, but it must not be
misconstrued as easy or fast.12 Integrating these principles into
clinical treatment protocols can prevent common but inadvertent errors, while
improving treatment outcomes—a win-win situation for both patients and
practitioners.

STACY A. MATSUDA, RDH, BS, MS, is a clinical instructor at Oregon Health & Science University School of Dentistry in Portland and has been in periodontal practice for more than 35 years. She directs the Pacific NW Institute, working with faculty and clinicians to advance the standard of care in nonsurgical therapy through courses and faculty development. Matsuda is a recipient of the Hu-Friedy/American Dental Hygienists' Association Master Clinician Award. She is also a Dimensions of Dental Hygiene Editorial Advisory Board member.